JP2001086516A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate a false color with a spatial frequency of (1/4) fsv in the chroma signal processing. SOLUTION: A delay circuit 20 of the image pickup device receives a full line image pickup signal read from a CCD image sensor and gives signals [H0D]-[H5D] by six consecutive lines to a vertical spatial phase synchronization filter 37 via a horizontal spatial phase synchronization filter 36. The filters 36, 37 apply synchronization of the spatial phases in the horizontal and vertical directions, signals S1r, S2r, S1b, S2b are generated through arithmetic operations of S1r=Cy+G, S2r=Ye+Mg, S1b=Cy+Mg and S2b=Ye+G on the basis of each of pixel data Cy(cyan), Ye(yellow), G(green) and Mg(magenta) of the signals whose spatial phases are synchronized and given to a C process circuit 60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging device,
In particular, the present invention relates to an imaging device applied to a video camera using a complementary color mosaic color coding CCD.

[0002]

2. Description of the Related Art In a single-panel CCD color camera system, for example, in which a single solid-state image pickup device such as a CCD image sensor is used to pick up a color image, a CCD image sensor as an image pickup device is provided for each pixel. It is necessary to provide filters of different colors, so-called color coding filters.

FIG. 6 shows a specific example of a color arrangement structure of a complementary mosaic color coding filter as an example of such a color coding filter.
y represents cyan (blue-green), Ye represents yellow (yellow), G represents green (green), and Mg represents magenta (red-purple), and the i-th (0 ≦ i) of each line N0, N1,. X represents the color X of the j-th pixel (0 ≦ j) in the line Ni. For example, G12 is the color G of the second pixel of the line N1.
(Green). In the example of FIG. 8, the horizontal (horizontal) direction is repeated at a two-pixel cycle, for example, Cy, Ye, Cy, Ye,..., And the vertical (vertical) direction is, for example, Cy, Ye.
G, Cy, Mg,..., Are repeated in a four-pixel cycle (four-line cycle). That is, the horizontal repetition cycle is two pixels, and the vertical repetition cycle is four lines.

FIG. 7 is a block diagram showing an example of a camera signal processing system of a video camera apparatus which is an image pickup apparatus using the CCD image sensor 102 having such a complementary color mosaic color coding filter.

[0005] In FIG. 7, an image pickup signal obtained by image pickup by a CCD image sensor 102 as an image pickup device through an optical system 101 including a lens of a camera unit and a mechanical shutter and the like, and photoelectrically converted is converted into a CDS (correlation) signal. Double sampling) circuit, GCA (gain control amplifier),
The signal is sent to the delay circuit 120 via the front end circuit 103 including an A / D (analog / digital) converter and the like. A read pulse signal from the timing generation circuit 106 is supplied to the CCD image sensor 102, and a sampling pulse, an A / D conversion drive pulse, and the like from the timing generation circuit 106 are supplied to the front end circuit 103. A control signal from the system control circuit 107 is supplied to the timing generation circuit 106, and a delay circuit 120
Also, a control signal from the system control circuit 107 is supplied. The output signal from the delay circuit 120 is
The signal is sent to the Y (luminance) process circuit 140 and the C (chroma) process circuit 160 via 0. A control signal from the system control circuit 107 is also supplied to the Y process circuit 140 and the C process circuit 160.

In the system shown in FIG. 7, the field read of the interlaced scan CCD is performed, and as shown in FIG. 8, adjacent pixel data of two lines in the vertical direction on the CCD are added, and Are read out as shown in FIG. This is also called two-line mixed reading. Thus, when two lines N0 + N1, N2 + N3,... Are mixed and added and read out in one field, N1 + N in the next field
2, N3 + N4,... Are mixed and read. Here, for each pixel to be mixed and added, Cy + G
Is S1r, Ye + Mg is S2r, and Cy + Mg is S1b, Ye +
G is S2b.

[0007]

By the way, FIG.
FIG. 10 shows chroma signal processing including the C process circuit 160 of FIG. 7 and its peripheral circuits. In FIG. 10, the delay circuit 120 includes two 1Hs (one horizontal period, one line).
No delay signal [HH0D] using delay elements 121 and 122,
The 1H delay signal [HH1D] and the 2H delay signal [HH2D] are extracted and sent to the preprocessing circuit 130. Preprocessing circuit 130
Then, the signals [HH0D] and [HH2D] are added by an adder 131, and halved by a １ ／ multiplier 132 (([HH0D] + [HH2
D]) / 2, and is sent to the C process circuit 160. The 1H delay signal [HH1D] is sent to the C process circuit 160 as it is as a signal to be processed. C process circuit 1
In 60, the 1H delay signal [HH1D] and the signal ([HH0D] + [HH2
D]) / 2 is sent to the post-processing circuit 162 via the horizontal spatial phase synchronization filter 161, and the output from the post-processing circuit 160 is extracted. The horizontal spatial phase synchronization filter 161 has a tap coefficient of (1,0,3) / (3,0,1) for the filter operation. For example, when looking at the signal of the line N2 + N3 in FIG. Performing the filter operation of tap coefficients (1, 0, 3) means that Cy20 + Mg30
Is weighted by 1 and Cy22 + Mg32 is weighted by 3 to be added (and may be further normalized by dividing by a sum of coefficients, etc.). As a result, the spatial phase in the horizontal direction is synchronized.

In the chroma signal processing shown in FIG. 10, a signal [HH1D] and a signal ([HH0D] + [HH2] whose vertical spatial phases are synchronized by the delay line of the delay circuit 120 are used.
D]) / 2, horizontal spatial phase synchronization filter 1
61, the horizontal spatial phase is synchronized with each of these signals S1 and S2. In this way, the signal S1 in which the vertical and horizontal spatial phases are synchronized
Signals r, S2r, S1b, and S2b are processed by a post-processing circuit 162 to create a chroma signal.

In this case, the signal [HH1D] and the signal ([HH0D] +
When [HH2D]) / 2 is described in units of pixel rate of the CCD image sensor 102, [HH1D] = N2 + N3 ([HH0D] + [HH2D]) / 2 = ((N0 + N1) + (N4 + N5 )) / 2, and at the pixel rate on the CCD, a chroma signal is created based on data of six lines (N0 to N5) in the vertical direction. That is, in the vertical direction, when expressed by filter tap coefficients, the filter operation of (0,0,2,2,0,0) / (1,1,0,0,1,1) is performed. Become. Therefore, in the camera signal processing system using the conventional field readout method, in the chroma signal processing, if the sampling frequency in the vertical direction of the CCD pixel rate is fsv,
The spatial frequency band (1
/ 4) There is a problem that a false color is generated in fsv.

The present invention has been made in view of the above problems, and has been made in consideration of the spatial frequency (1/1/3) in chroma signal processing.
4) An object of the present invention is to provide an imaging device capable of eliminating a false color of fsv.

[0011]

In order to solve the above-mentioned problems, an image pickup apparatus according to the present invention comprises: an image pickup device having a color coding filter; A spatial phase synchronizing means for synchronizing the spatial phase in the vertical direction, and a synthesizing means for creating a synthetic signal based on the signal in which the horizontal and vertical spatial phases from the spatial phase synchronizing means are synchronized. And performing a chroma process on the signal from the synthesizing means.

Here, the color coding filter may be a complementary color mosaic color coding filter. The complementary color mosaic color coding filter includes a first line in which Cy and Ye are alternately repeated, and G and Mg. Are alternately repeated, a third line in which Cy, Ye is alternately repeated, and M
Use of a filter having a horizontal 2 pixel × vertical 4 line composed of a fourth line in which g and G are alternately repeated is used as a repetition unit.

[0013] The synthesizing means may include Cy (cyan) and Ye (yellow) of each pixel data of the signal whose horizontal and vertical spatial phases have been synchronized from the spatial phase synchronizing means.
, G (green), and Mg (magenta), new signals S1r, S2r, S1b, and S2b are created by calculating S1r = Cy + G, S2r = Ye + Mg, S1b = Cy + Mg, and S2b = Ye + G.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an imaging apparatus according to the present invention will be described below with reference to the drawings. FIG.
FIG. 1 is a block diagram illustrating an example of a system configuration of a video camera device as an embodiment of an imaging device according to the present invention. FIG. 2 is a block diagram extracting and showing a configuration of a portion related to chroma signal processing, which is a main portion of the present embodiment.

In FIG. 1, the optical system 11 of the camera unit is
This optical system 1 is composed of a lens, a mechanical shutter, etc.
The optical image passing through 1 is picked up by a CCD image sensor 12, which is an image pickup device, and photoelectrically converted. This CCD
The image sensor 12 is capable of reading all pixels, and specifically reads all pixels by reading frames of an interlaced scan CCD. This interlaced scan and frame readout 2
The signal of the field is an image exposed at the same time by the mechanical shutter of the optical system 11.

An image signal obtained from the CCD image sensor 12 is supplied to a front end circuit 13. This front-end circuit 13 is a CDS (correlation 2) for detecting charges of each pixel photoelectrically converted and accumulated by the CCD.
Double sampling) circuit, GCA (gain control amplifier), A
/ D (analog / digital) converter, etc., and the output signal from the front end circuit 13 is
The signal is sent to the delay circuit 20 via the memory control circuit 14.
The memory 15 is connected to the memory control circuit 14.
The memory 15 is for rearranging the signals read out from the frame from the CCD image sensor 12 into spatial array data on the CCD.

A read pulse signal from the timing generation circuit 16 is supplied to the CCD image sensor 12, and a sampling pulse, an A / D conversion drive pulse, and the like from the timing generation circuit 16 are supplied to the front end circuit 13. . A control signal from the system control circuit 17 is supplied to the timing generation circuit 16, and a control signal from the system control circuit 17 is also supplied to the delay circuit 120.

Here, the frame reading operation from the CCD image sensor 12 and the rearrangement operation in the memory 15 will be described with reference to FIGS. FIG. 3 is a diagram showing an image of frame readout on the CCD image sensor 12, in which all the lines N
All the individual pixels of 0, N1,... Are read out,
By interlaced scanning every other line,
The CCD output signal is, as shown in FIG.
Are divided into a first field F1 of 0, N2,... And a second field F2 of odd lines N1, N3,. . The memory control circuit 14 writes / writes the signals of these two fields F1 and F2 to the memory 15 /
By performing the read control, the data is rearranged and output in the spatial arrangement order on the CCD as shown in FIG. That is, the output signal (FIG. 5) from the memory control circuit 14 is a frame image signal according to the line order (N0, N1,...) On the CCD.

Returning to FIG. 1, the output signal from the delay circuit 20 is sent to the Y (luminance) process circuit 40 and the C (chroma) process circuit 60 via the preprocessing circuit 30. A control signal from the system control circuit 17 is also supplied to the Y process circuit 40 and the C process circuit 60.

FIG. 2 shows a configuration of a portion related to chroma signal processing which is a main portion of the present embodiment. In FIG. 2, the delay circuit 20 uses five 1H (one horizontal period, one line) delay elements 21 to 25, and outputs a signal without delay [H0D] and a 1H delay signal [H1D] to 1H.
The 5H delay signal [H5D] is extracted and sent to the preprocessing circuit 30. The correspondence between these signals [H0D] to [H5D] and each of the lines N0 to N5 in FIG.
[H0D] is on line N5 and 1H delay signal [H1D] is on line N
4,... 5H delay signal [H5D] respectively correspond to line N0.

In the preprocessing circuit 30, the signals [H0D] to [H5]
D], the signals [H0D] and [H1D] are added by the adder 31.
The signals [H2D] and [H3D] are added by the adder 32, and the signals [H4D] and [H4D] are added.
[H5D] is added by the adder 33, and the output from the adder 31 and the output from the adder 33 are added by the adder 34 to form [1/2].
The output signal ([H0D] + [H1D] + [H4D] + [H5D]) / 2 from the multiplier 35 and the output signal ([[ H2D] + [H3D]) to the Y process circuit 40. The output signal from the adder 32
([H2D] + [H3D]) is the current processing target signal. Also,
The signals [H0D] to [H5D] are passed through the horizontal spatial phase synchronization filter 36 to the vertical spatial phase synchronization filter 37.
Through the synthesizing circuit 38, and the synthesizing circuit 3
The signal S1r / S2r and the signal S1b / S2b are sent to the C process circuit 60. Here, the tap coefficient in the filter operation in the horizontal spatial phase synchronization filter 36 is (1,0,3) / (3,0,1), and the filter operation in the vertical spatial phase synchronization filter 37 is Is (1,0,4,0,3,0) / (0,3,0,4,0,1). The synthesizing process in the synthesizing circuit 38 means that the signals S1r, S2r, S1b, and S1b are based on the complementary color data (Cy, Ye, G, and Mg) in which the spatial phases in the horizontal and vertical directions are synchronized.
This is the process of creating S2b, and the signals S1r, S2r, S1b, S
2b is represented by S1r = Cy + G, S2r = Ye + Mg, S1b = Cy + Mg, and S2b = Ye + G.

In the C process circuit 60, the signals S1r / S2r and S1b / S2b from the synthesizing circuit 38 are sent directly to the post-processing circuit 62, bypassing the horizontal spatial phase synchronization filter 61. This is because the horizontal phase of the horizontal direction has already been synchronized by the pre-processing circuit 30, and the existing C
Horizontal spatial phase synchronization filter 6 of process circuit 60
1 is unnecessary.

The operation of the pre-processing circuit 30 as a main part in the chroma signal processing having such a configuration will be described in more detail. First, the synchronization of the spatial phase by the horizontal spatial phase synchronization filter 36 and the vertical spatial phase synchronization filter 37 is performed by, for example, the CC shown in FIG.
In a signal rearranged in accordance with the pixel array on D, for example, four pixels Cy22, Ye23, Mg32,
Instead of G33, data (pixel value) of each complementary color (Cy, Ye, Mg, G) to be arranged at the point p at the center position of these pixels is obtained by interpolation.

Hereinafter, in order to explain a specific example, the vertical spatial phase of the point p for synchronizing the spatial phase is represented by V
Let p be the spatial phase in the horizontal direction. When the suffix of each pixel, that is, “23” such as Ye23 represents the vertical phase “2” and the horizontal phase “3”, each pixel data at the position of the point p is CyVpHp, YeVpHp, MgVpHp, It can be expressed as GVpHp. In the example of FIG. 5, Vp = 2.5 and Hp = 2.5. Here, as one specific example, a case where CyVpHp is obtained by an interpolation calculation or a filter calculation will be described. In this case, first, the horizontal spatial phase synchronization filter 3
6, the pixel data Cy0 having a horizontal phase of Hp (= 2.5)
Find Hp, Cy2Hp, Cy4Hp. These are the tap coefficients (3,
0,1), that is, Cy0Hp = 3 * Cy02 + 0 * Ye03 + 1 * Cy04 Cy2Hp = 3 * Cy22 + 0 * Ye23 + 1 * Cy24 Cy4Hp = 3 * Cy42 + 0 * Ye43 + 1 * Cy44. Usually, tap coefficient 0
Is omitted, and Cy0Hp = 3 * Cy02 + 1 * Cy04 Cy2Hp = 3 * Cy22 + 1 * Cy24 Cy4Hp = 3 * Cy42 + 1 * Cy44. As the tap coefficient of the horizontal spatial phase synchronization filter 36, (3,0,1) is also used for Mg, but the tap coefficient of (1,0,3) is used for Ye and G. You.

The pixel data (for example, Cy0Hp, Cy2Hp, Cy4Hp) whose horizontal spatial phase has been synchronized by the horizontal spatial phase synchronizing filter 36 is sent to the vertical spatial phase synchronizing filter 37, , The pixel data having a vertical phase of Vp (= 2.5), for example, CyVpHp is obtained. This can be obtained by performing a filter operation of the tap coefficients (1, 0, 4, 0, 3, 0), that is, a calculation of CyVpHp = 1 * Cy0Hp + 4 * Cy2Hp + 3 * Cy4Hp. YeVpHp
(1,0,4,0,3,0) is also used as a tap coefficient when calculating MgVpHp, and a tap coefficient when calculating MgVpHp and GVpHp is (0,3,0,4,0,1). Become.

Next, the synthesizing circuit 38 outputs, for example, CyVpH, in which the horizontal and vertical spatial phases are synchronized as described above.
Complementary colors such as p, YeVpHp, MgVpHp, GVpHp (Cy, Ye, Mg,
Using the data of G), S1r = Cy + G, S2r = Ye + Mg, S1b = Cy + Mg, and S2b = Ye + G are calculated to generate the signals S1r, S2r, S1b, and S2b, and the post-processing circuit 62 of the C process circuit 60 Send to

The signals S1r, S2r, S from the synthesizing circuit 38
Since 1b and S2b are created based on the 2 × 2 pixels of the pixel array on the CCD, the sampling frequency in the vertical direction is f
When sv is set, no false color occurs at the frequency (1/4) fsv.

The present invention is not limited to the above-described embodiment. For example, in the above-described embodiment, an example of application to a video camera device has been described. In the above embodiment, the signal processing of the frame readout method using the interlaced scan CCD has been described. However, a system capable of reading data independently of each line of the complementary color mosaic color coding CCD is also described. Applicable. Further, the pixel arrangement of the complementary color mosaic color coding is not limited to the above embodiment, and may be another arrangement.
The present invention is also applicable to a case where color coding filters of three primary colors are used. In addition, it goes without saying that various changes can be made without departing from the spirit of the present invention.

[0029]

According to the image pickup apparatus of the present invention, the spatial phase in the horizontal and vertical directions is synchronized based on the output from each line of the image pickup element having the color coding filter and the image pickup element. Spatial phase synchronizing means, and synthesizing means for creating a synthesized signal based on the signal in which the horizontal and vertical spatial phases from the spatial phase synchronizing means are synchronized, and outputting the signal from the synthesizing means. By performing the chroma processing, it is possible to eliminate a false signal of (1/4) fsv in the chroma signal, and the image is greatly improved.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a video camera device to which an embodiment of the present invention is applied.

FIG. 2 is a block diagram extracting and showing a configuration of a portion related to chroma signal processing which is a main portion of the embodiment of the present invention.

FIG. 3 is a diagram showing an image of frame reading on a CCD image sensor.

FIG. 4 is a diagram showing a CCD output signal when all pixels are read out by two field signals by interlaced scanning of a CCD image sensor.

5 is a diagram showing signals after rearranging the CCD output signals of FIG. 4 according to the pixel arrangement on the CCD image sensor.

FIG. 6 is a diagram illustrating an example of a complementary mosaic color coding filter on a CCD image sensor.

FIG. 7 is a block diagram showing an example of a camera signal processing system of a conventional video camera device.

FIG. 8 is a diagram for explaining two-line mixed reading of the CCD image sensor.

FIG. 9 is a diagram showing a CCD output signal obtained by two-line mixed reading of the CCD image sensor.

FIG. 10 is a block diagram extracting and showing a configuration of a portion related to conventional chroma signal processing.

[Explanation of symbols]

12 CCD image sensor, 13 front end circuit, 14 memory control circuit, 15 memory, 2
0 delay circuit, 21 to 25 1H delay element, 30 preprocessing circuit, 31 to 34 adder, 36 horizontal spatial phase synchronization filter, 37 vertical spatial phase synchronization filter, 38 synthesis circuit, 40 Y process circuit, 60 C process circuit

Claims (5)

[Claims] An image sensor having a color coding filter; a spatial phase synchronizing means for synchronizing a spatial phase in a horizontal direction and a spatial phase in a vertical direction based on an output from each line of the image sensor; A synthesizing unit for generating a synthesized signal based on the signal obtained by synchronizing the horizontal and vertical spatial phases from the synchronizing unit, and performing chroma processing on the signal from the synthesizing unit. . 2. The imaging apparatus according to claim 1, wherein the color coding filter is a complementary color mosaic color coding filter. 3. The complementary mosaic color coding filter comprises a first line in which Cy (cyan) and Ye (yellow) are alternately repeated, and a second line in which G (green) and Mg (magenta) are alternately repeated. A filter having a horizontal 2 pixel × vertical 4 line composed of a line, a third line in which Cy and Ye are alternately repeated, and a fourth line in which Mg and G are alternately repeated is a unit of repetition. The imaging device according to claim 2, wherein: 4. The synthesizing means includes: Cy (cyan), Ye (yellow), and G of each pixel data of a signal in which the horizontal and vertical spatial phases from the spatial phase synchronizing means are synchronized.
3. The method according to claim 2, wherein new signals S1r, S2r, S1b, and S2b are created by calculating S1r = Cy + G, S2r = Ye + Mg, S1b = Cy + Mg, and S2b = Ye + G based on (green) and Mg (magenta). Imaging device. 5. The image pickup apparatus according to claim 1, wherein the image pickup element scans an odd line and an even line individually and reads out the frame.